A study on wall-to-bed heat transfer in a conical fluidized bed combustor

In this study, the flow characteristics and wall-to-bed heat transfer in a conical fluidized bed combustor (FBC) of height 0.8 m and cone angle of 30° were analyzed numerically and the results were compared to experimental ones. A two fluid Eulerian-Eulerian model coupled with kinetic theory of granular flow (KTGF) was used to simulate both hydrodynamic characteristics and heat transfer in a conical FBC. Hydrodynamic characteristics such as sand volume fraction, bed expansion, and pressure drop between two points at the cone part as well as heat transfer coefficient were compared to experimental data obtained under various operating conditions such as different superficial gas velocities and granular temperature models. Both heat transfer coefficient and pressure drop increased with increasing gas velocity. Use of a phase property model for granular temperature with slip conditions at the wall resulted in no clear effect in case of heat transfer coefficient, whereas there was better agreement between the experimental and numerical results for bed pressure drop when a partial differential equation model was used.